The present invention relates generally to peptide analogues of insulin, and more specifically to methods for treating diabetes using peptide analogues derived from residues 9-23 of human insulin B chain.
Insulin dependent diabetes mellitus (IDDM) is an organ specific autoimmune disease affecting close to a million people in different age groups in the United States. The disease is characterized by extensive destruction of the insulin producing beta cells in the pancreatic islets and dysregulation of glucose metabolism leading to frank diabetes. The defining feature of IDDM is the lymphocytic infiltration of the islets. Among the invading cells, T cells appear to be one of the major mediators of autoimmune destruction.
Type I diabetes is further characterized by increased levels of antibodies to various islet associated antigens, including insulin. GAD65, GAD67 and ICA512. These antibodies can be detected much before frank disease, and an immune response to such antigens can be used as a predictor for impending diabetes in patients with susceptible genetic (HLA) haplotypes.
Currently, patients are dependent on insulin injections to maintain normoglycemia. Insulin is a polypeptide hormone consisting of two disulfide-linked chains, an A chain consisting of 21 amino acid residues and a B chain of 30 residues. While administration of insulin provides significant benefits to patients suffering from diabetes the short serum half-life of insulin creates difficulties for maintaining proper dosage. The use of insulin also can result in a variety of hypoglycemic side-effects and the generation of neutralizing antibodies.
In view of the problems associated with existing treatments of diabetes, there is a compelling need for improved treatments that are more effective and are not associated with such disadvantages. The present invention exploits the use of peptide analogues which antagonize a T cell response to insulin to effectively treat diabetes, while further providing, other related advantages.
The present invention provides compounds and methods for treating and preventing diabetes. Within certain aspects, the present invention provides peptide analogues comprising residues 9 to 23 of human insulin B chain (SEQ ID NO:2), wherein the peptide analogue differs in sequence from native human insulin B chain residues 9 to 23 due to substitutions at between 1 and 4 amino acid positions. Such substitutions may be made at one or more residues selected from the group consisting of residues 12, 13, 15 and 16, with or without additional substitutions at other residues. Within certain preferred embodiments, such substitutions may occur at two or three amino acid residues within residues 9 to 23 of insulin B chain. Substitutions may also IS occur at residue 19. Substitutions are preferably non-conservative, and analogues wherein residue 12, 13, 15, 16 and/or 19 are altered (to, for example, alanine) are preferred. Analogues further comprising residue 24 of insulin B chain are also preferred. In certain other embodiments, the peptide analogues comprise no more than 18 residues, no more than 16 residues or no more than 15 residues of human insulin B chain.
Within further embodiments, the peptide analogues consist essentially of residues 9 to 23 or 9 to 24 of human insulin B chain (SEQ ID NO:2), wherein the peptide analogue differs in sequence from native human insulin B chain residues 9 to 23 due to substitutions at between 1 and 4 amino acid positions, and wherein at least one substitution occurs at a residue selected from the group consisting of residues 12, 13, 15 and 16.
Within further aspects, pharmaceutical compositions are provided, comprising a peptide analogue as described above in combination with a physiologically acceptable carrier or diluent.
The present invention further provides methods for treating and/or inhibiting the development of diabetes, comprising administering to a patient a therapeutically effective amount of a pharmaceutical composition as described above.
These and other aspects of the invention will become evident upon reference to the following detailed description and attached drawings. In addition, various references are set forth below which describe in more detail certain procedures or compositions. These references are incorporated herein by reference in their entirety as if each were individually noted for incorporation.